Prescription opioid abuse is a growing public health epidemic in the US, contributing to an estimated 15,000 deaths and more than $55 billion in societal costs per year. In response, states are increasingly managing CS abuse with Medicaid Lock in Programs (MLIP). The North Carolina (NC) Recipient Management MLIP, initiated in October of 2010, was designed to reduce fraudulent prescription claims for opioids and anxiolytics, while improving continuity of treatment among patients needing aggressive pain management. The program limits eligible patients to a single provider and a single pharmacy for a 12 month period. To date, algorithms to identify patients appropriate for the NC and other MLIPs have been based primarily on the best clinical judgment of state Medicaid personnel. Separate from the MLIP, NC also implemented the Controlled Substances Reporting System (CSRS), which monitors all prescriptions for CS, regardless of payer type. Combining data from the NC MLIP and the CSRS creates a unique opportunity to: (1) assess the implementation of the NC MLIP and (2) examine changes in CS prescriptions filled among individuals in the NC MLIP, regardless of insurer. Therefore, we propose to examine utilization and overdose outcomes in the current NC MLIP. Specific Aim #1, will use interviews with key stakeholders-program administrators, physicians, and pharmacists-to perform a process assessment in order to determine the context in which the NC MLIP operates. Specific Aims #2 and #3 will use Medicaid claims data and the CSRS to examine the effect of the NC MLIP on the number of CS prescription and prescribers, while Specific Aim #4 examines the effect of the NC MLIP on CS overdose. MLIPs such as the one in NC will continue to be developed and implemented by many states. A rigorous evaluation of the NC MLIP is critical to building the foundation for developing effective policies that can reduce the devastating consequences of prescription drug abuse in the US. The proposed study will capitalize on a unique and powerful database to examine the effect of the NC MLIP on CS use and abuse. The results of this study have the potential to substantially reduce the cost of CS abuse in terms of human lives and financial resources.